Although I do have a point to add on just for the sake of it.....Its concerning the limitation of the Merge Command.

"The merge command could be used only on those tables which do not have duplicate records."

Actually this point is more of a reminder to all those creating tables to have a primary key to them. The way I look at it, once you keep in check that your database is atleast in the 1NF, then the Merge can be used and the above mentioned limitation would never be a concern :D